@article{fdi:010058183,
  title = {{P}artial self-reversal of {TRM} in baked soils and ceramics from {E}cuador},
  author = {{R}operch, {P}ierrich and {C}hauvin, {A}. and {V}aldez, {F}rancisco},
  editor = {},
  language = {{ENG}},
  abstract = {{P}artial self-reversed thermoremanent magnetizations ({SRTRM}s) were observed in samples of baked soils, hearths and ceramics from the {R}umipamba archeological site near {Q}uito ({E}cuador) and ceramics from sites near the town of {E}smeraldas ({E}cuador). {T}he {SRTRM}s were recognized at room temperature on few samples but cooling the samples in liquid nitrogen enhanced the intensity of the {SRTRM} and measurement at 77 degrees {K} enables its rapid detection in many samples from these sites. {A}lternating field demagnetization of the {SRTRM} indicate median destructive field of the order of 50 m{T} and thermal demagnetization give unblocking temperatures in the temperature range 280-380 degrees {C}. {T}he magnetic carriers of the {SRTRM} are stable to heating in air or in vacuum up to 600 degrees {C} suggesting that titanomaghemite should not be the magnetic carrier of the {SRTRM}. {T}he studied baked clays and ceramics contain detrital material of mainly volcanic origin. {T}i-poor titanomagnetite is the main magnetic carrier identified by strong field data or susceptibility measurements versus temperature. {I}lmeno-hematite grains were recognized with microscope observations under reflected light. {S}canning electron microscope observations with energy dispersive {X}-ray spectrometry indicate a {T}i/{F}e ratio corresponding to an ilmenite content of similar to 0.55. {W}e also compared the magnetic properties of the partially self-reversed baked clays with those of the self-reversed {P}inatubo pumices. {T}he {SRTRM}s were measured upon cooling from room temperature to 20 degrees {K} with the {MPMS}. {U}pon cooling to 20 degrees {K} the {SRTRM} show a nearly tenfold increase in intensity with respect to the room temperature measurement. {T}he baked clay and ceramics from {E}cuador carrying the {SRTRM} share similar magnetic properties with the {P}inatubo pumices (unblocking temperatures, low temperature behavior) supporting the interpretation that detrital hemoilmenite originating from the {H}olocene activity of the numerous {E}cuadorian volcanoes is the main carrier of the {SRTRM} in the archeological samples. {I}n some samples, anisotropy tensors of {SRTRM} show large anisotropy degree (>2). {T}he high anisotropy observed when the total magnetization is the sum of a normal thermoremanent magnetization ({TRM}) and a {SRTRM} is likely amplified because the anisotropy carried by the {SRTRM} is larger than the one carried by the normal component. {A} component of {SRTRM} may be hidden in archeological materials containing detrital hemoilmenites related to dacitic/andesitic volcanism and this may affect the determination of paleointensity of the earth magnetic field especially when non thermal method are used.},
  keywords = {{P}aleomagnetism ; {S}elf-reversal ; {T}hermoremanent magnetization ; {A}rcheomagnetism ; {I}lmeno-hematite ; {M}agnetic mineralogy},
  booktitle = {},
  journal = {{P}hysics of the {E}arth and {P}lanetary {I}nteriors},
  volume = {210},
  numero = {},
  pages = {8--20},
  ISSN = {0031-9201},
  year = {2012},
  DOI = {10.1016/j.pepi.2012.08.004},
  URL = {https://www.documentation.ird.fr/hor/fdi:010058183},
}